1. Field of the Invention
The present invention relates to an automatic medicine packaging machine, and more particularly, to an apparatus for precisely detecting that a tablet is dropped in a last hopper so that packaging speed of tablets is increased and operation of a shutter and a sealer is precisely performed.
2. Description of the Related Art
Generally, an automatic medicine packaging machine indicates an apparatus for automatically packaging medicines into doses.
The structure and operation of a conventional automatic medicine packaging machine will be described with reference to FIG. 7 schematically depicting the conventional automatic medicine packaging machine.
As shown in FIG. 7, the conventional automatic medicine packaging machine includes a plurality of tablet cassettes 200 installed on a shelf disposed at the upper side of a main body 100, a hopper 300 having a last hopper 301 installed at the lower side of the tablet cassettes 200, a pair of packaging sheet rolls 400 disposed at the lower lateral sides of the hopper 300, a printer 500 installed at the lower side of one of the packaging rolls 400 to print information such as the patient name, how to take the medicine, or the like, a pair of driving rollers 600 installed below the hopper 300, a sealer 700 disposed between the hopper 300 and the driving rollers 600 to seal the packaging sheets to form a series of medicine packets R, and a punch 800 disposed below the sealer 700 to form holes in the series of medicine packets R.
In such conventional automatic medicine packaging machine, the tablets, dropped into the hopper 300 from the tablet cassettes 200, are inserted between a pair of packaging sheets drawn from the packaging rolls 400 by the driving rollers 600, and the sealer 700 seals the packaging sheets traveling downward to finish a series of medicine packets R and to discharge the series of medicine packets R through the lower side of the main body 100.
The discharged series of medicine packets R is fed from the lower side of the main body 100 to the lateral side of the main body 100 by a feeder 900 and discharged out through the lateral side of the main body 100.
The automatic medicine packaging machine and its devices are controlled by a controller 100a. 
FIG. 8 is an enlarged rear perspective view illustrating the conventional automatic medicine packaging machine.
As shown in the drawing, the conventional automatic medicine packaging machine includes the last hopper 301 disposed at the lower side of the hopper 300 installed at a main frame 101 of the main body 100, a shutter 302 installed in the last hopper 301, and a shutter driving part 303 for driving the shutter 302 to open and close the last hopper 301.
The shutter driving part 303 includes a rotation cam 305 rotated by a motor 304, a rotation link 306 connected to the rotation cam 305, a connection link 307 connected to the rotation link 306, a rotation shaft 308 coupled with a connection link 307 and penetrating the main frame 101 to rotate, and a trigger 309 installed to the end of the rotation shaft 308 and rotated by the rotation shaft 308.
The trigger 309 rotates to press a crank bar 302a installed to the upper outer side of the shutter 302 so that the shutter 302 is opened and the tablets accommodated in the last hopper 301 are discharged through the lower side thereof.
However, the conventional automatic medicine packaging machine has the following disadvantages.
Since the time within which the medicine tablets are discharged from the respective tablet cassettes and are dropped in the last hopper is not uniform, a time delay is set to the shutter opening time and the sealing time of the sealer. Due to the preset time delay, the packaging speed of the medicine tablets is significantly slowed and setting of the delay time is very difficult and unreliable.
Due to the unreliable time delay, the shutter and the sealer cannot be precisely driven so that various errors occur during the packaging of the medical tablets.